This invention relates to the diagnosis of disorders caused by mental stress. More specifically, it relates to a method for assaying an antigen related to disorders caused by mental stress in a human body fluid sample by an immunoassay technique with the use of an antibody or fragment thereof raised against a protein related to mental stress which is secreted under mental stress, and a diagnostic kit for said method.
In general, stress is a cause of fatigue, insomnia, uneasiness, irritation, and anxiety, etc. The term "stress" refers to a state wherein an individual is placed under physical or mental pressure. External and internal factors causing stress include:
(1) physicochemical factors such as cold, heat, noise and hypoxia:
(2) biological factors such as starvation, fasting vitamin deficiency, hard physical labor and pregnancy; and
(3) psychological and social factors such as family problems, occupational problems, poor living conditions, problematic personal relations and financial problems. In contemporary society, stress caused by psychological and social factors is an extremely serious problem.
According to "DSM-III-R (Diagnostic and Statistic Manual for Mental Disorders)" published by the U.S. Psychiatric Society, for example, intensities of psychological and social stress are differentiated as transient or persistent phenomena. Stress arising from social or psychological factors is also differentiated as pertaining to children, adolescents or adults. On the basis of such criteria, the type and intensity of stress can be roughly evaluated and based on the evaluation a therapeutic schedule, crisis intervention or other assistance strategy can be determined. Stress caused by transient phenomena tends to be readily apparent as the factors leading to the condition are easy to observe. In contrast, mental stress resulting from persistent phenomena is often overlooked. Such long term stress can constitute an etiololgy of stress related disease.
However, it can take a time to give a definitive diagnosis of stress as a causative factor in disease since standards for the diagnosis of mental stress vary. Therefore, it will be of great benefit to be able to diagnose an accumulation of mental stress efficiently and easily.
The present inventors performed a sensory evaluation of taste perception over a period of time by using a computerized time-intensity on-line system and subsequently reported that sensitivity to bitterness is lowered under mental stress [Mizuma et al., "the Japanese Journal of Taste and Smell Research", Vol. 3: 340-343, 1994]. Namely, it is reported that, when an aqueous solution of quinine, i.e., a bitter substance, is held in the mouth in a mentally stressed state, perception of bitterness is reduced and any aftertaste lasts for a shortened period of time. That is to say, subjects under mental stress are less sensitive to bitter substances in the mouth.
Although in daily life most people experience changes in taste sensitivity due to physical or psychological conditions, few attempts have been made to clarify the reasons therefor. For example, A. I. Spielmam reports that after hard exercise, the buffer action of the saliva is enhanced and, this accounts for the reason why sensitivity to sourness is reduced (Journal of Dent. Res., 69:838-843, 1990).
With respect to substances reducing bitterness or a sensitivity to bitterness, there have been known proline rich proteins (PRPs) which are contained in the saliva and regulate the bitterness of tannic acid (J. I. Glendinning, Chem. Sens., 17:1-12, 1992). It is also reported that VEG protein secreted from von Ebner's glands in the oral cavity has a function of transporting fat-soluble substances to taste sensitive organs (H. Schemale et al., Nature 343:366-369, 1990). However, there have been no reports about the relation between these substances and stress so far.